Pope Francis arrives for a prayer at Rome's Santa Maria Maggiore basilica early on his first full day as the head of the world's 1.2 billion Catholics. / AFP/Getty Images

by Marco della Cava and John Bacon, USA TODAY

by Marco della Cava and John Bacon, USA TODAY

VATICAN CITY -- Pope Francis could have been excused for sleeping in Thursday, a day after shocking the world with a series of pontiff firsts: a Jesuit from Latin America who chose a name honoring St. Francis of Assisi.

But the newly elected leader of the world's 1.2 billion Catholics was up early, praying for 30 minutes at Rome's Santa Maria Maggiore church. Outside, a crowd of around 150 faithful cheered.

The main item on Francis' agenda was his inaugural Mass in the Sistine Chapel, where a day earlier cardinals chose him as the 266th pope. Francis displayed how different he would be as a pastor, giving the cardinals an off-the-cuff homily about the need to walk with God, build up his church and confess - at one point referring to children building sand castles on the beach.

Vatican officials confirmed that Pope Francis' official installation Mass will take place Tuesday at St. Peter's Square. The White House said Vice President Biden, who is Catholic, will lead a U.S. delegation to Rome for the installation ceremony.

At a Vatican press conference Thursday, details also emerged about Francis' humble approach to his new position. After appearing on the balcony, Francis declined to use a private car with the license plate SCV1 - Vatican City 1 - to return to the cardinals' dormitory. "He said, 'I'll take the bus (that shuttled the cardinals to the Sistine Chapel), since that's the way I came here,'" said spokesman Rev. Thomas Rosica.

Pope Francis then went to pay pick up his belongings and pay his bill at the clerical hotel he stayed at before the conclave, "because he wanted to be sure to give a positive example to his fellow cardinals," Rosica said.

"We'll get used to a new way of doing things," said Rosica, referring to the casual style with which the new pope buzzed around Rome, greeting well-wishers at each stop. "The security forces are here to work with the style of whoever is the new pope. Remember John Paul II, and how many rules he broke doing things his way with his own style."

Francis will stay on for a few days at a VIP apartment in the same Casa Santa Marta residence that hosted all the cardinals during the conclave. "It features a number of rooms (as compared to the simple one he stayed in as cardinal), which he will need for papal audiences," Rosica said.

Pope Francis also will go to the official residence and take off the papal seals on the doors - which prevented anyone from entering after Pope Benedict XVI left the premises - so work can officially begin on refurbishing it for the new pope.

Another significant item on the pope's to-do list is a visit with Benedict, the first pope emeritus in 600 years, who has been staying at the Vatican's fabled summer retreat, Castel Gandolfo, since his historic resignation last month.

Rosica said Francis will visit with the man he succeeded "some time in the coming days," and not Thursday as had originally been suggested. The two men did speak Wednesday night by phone after the election.

On Wednesday, throngs jamming St. Peter's Square roared with joy as Argentine Cardinal Jorge Mario Bergoglio, archbishop of Buenos Aires, stepped onto the balcony as the new pope.

"Brothers and sisters, good evening," he said to wild cheers. "You know that the work of the conclave is to give a bishop to Rome. It seems as if my brother cardinals went to find him from the end of the earth. Thank you for the welcome."

The crowd grew silent as Francis, 76, recited the Lord's Prayer and a Hail Mary. He asked the crowd to pray for him before he blessed them.

"Let us pray for the whole world," he said.

Moments later, the official Twitter account for the pope tweeted: "Habemus Papam Franciscum" - We have Pope Francis. It was retweeted more than 55,000 times in less than two hours.

Hours later, the Vatican updated the Holy See website with the first official portrait of the new pontiff and the Latin phrase announcing his selection. Besides English and Latin, the site is available in Spanish, Italian, French, Portuguese and German.

Francis' papacy is one of firsts: He is the first Jesuit, the first non-European in modern times and first Latin American pope. He also is the first to take the name Francis, for the saint devoted to the poor.

The Vatican's lead spokesman, Rev. Federico Lombardi, who like Pope Francis is a Jesuit, expressed surprise at Wednesday's choice.

"We're (Jesuits) not used to seeking office like this, so I was stunned at what happened yesterday as I saw my brother come out on the loggia," said Lombardi. "It's a great calling, but a calling none of us aspired to. It's a call of extreme service. The idea of a Jesuit priest is very strange, I wasn't prepared psychologically. We are used to serving, not being the ones in charge. But I see it as a special compliment."

Bergoglio reportedly received the second-most votes after Joseph Ratzinger - Pope Benedict XVI - in the 2005 papal election. Despite being Argentina's top church official, Bergoglio never lived in the ornate church mansion in Buenos Aires, preferring a simple bed in a downtown room heated by a small stove. For years, he took public transportation around the city and cooked his own meals.

It's been widely reported that he had a lung removed as a teen, but Vatican spokesman Rosica said Pope Francis "did not have a lung removed," but had an operation as a young man due to an infection.

The cardinals took five ballots over two days to reach their decision by the required two-thirds majority. The first vote took place late Tuesday. Two morning votes Wednesday brought similar results - black smoke from the Sistine Chapel's chimney that meant no decision on a new pope had been reached. Late Wednesday, the smoke was finally white and Vatican bells pealed.

President Obama offered "warm wishes" to the new pope.

"As a champion of the poor and the most vulnerable among us, he carries forth the message of love and compassion that has inspired the world for more than two thousand years - that in each other we see the face of God," Obama said in a statement.

James O'Rourke, a management professor at the University of Notre Dame, a Roman Catholic school in South Bend, Ind., said Francis will need a strategic vision, team-building and financial skills and what he calls "charismatic empathy."

Many North American Catholics want a greater role for women in the church, O'Rourke said, while many Europeans oppose such a move. Catholics in Latin America want more vibrant parishes and the fast-growing Catholic population in Africa needs more priests, he said.

Fittingly, Bergoglio's new namesake, St. Francis, is famous for his vision of a talking crucifix telling him, "Francis, rebuild my church."